<?php
/**
 * Zend Framework
 * LICENSE
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 * @category Zend
 * @package Zend_Validate
 * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 * @license http://framework.zend.com/license/new-bsd New BSD License
 * @version $Id: Issn.php 24593 2012-01-05 20:35:02Z matthew $
 */
/**
 *
 * @see Zend_Validate_Barcode_AdapterAbstract
 */
require_once 'Zend/Validate/Barcode/AdapterAbstract.php';

/**
 *
 * @category Zend
 * @package Zend_Validate
 * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 * @license http://framework.zend.com/license/new-bsd New BSD License
 */
class Zend_Validate_Barcode_Issn extends Zend_Validate_Barcode_AdapterAbstract {

    /**
     * Allowed barcode lengths
     * @var integer
     */
    protected $_length = array(8, 13);

    /**
     * Allowed barcode characters
     * @var string
     */
    protected $_characters = '0123456789X';

    /**
     * Checksum function
     * @var string
     */
    protected $_checksum = '_gtin';

    /**
     * Allows X on length of 8 chars
     * @param string $value The barcode to check for allowed characters
     * @return boolean
     */
    public function checkChars ($value) {
        if (strlen ($value) != 8) {
            if (strpos ($value, 'X') !== false) {
                return false;
            }
        }
        return parent::checkChars ($value);
    }

    /**
     * Validates the checksum
     * @param string $value The barcode to check the checksum for
     * @return boolean
     */
    public function checksum ($value) {
        if (strlen ($value) == 8) {
            $this -> _checksum = '_issn';
        } else {
            $this -> _checksum = '_gtin';
        }
        return parent::checksum ($value);
    }

    /**
     * Validates the checksum ()
     * ISSN implementation (reversed mod11)
     * @param string $value The barcode to validate
     * @return boolean
     */
    protected function _issn ($value) {
        $checksum = substr ($value,  - 1, 1);
        $values = str_split (substr ($value, 0,  - 1));
        $check = 0;
        $multi = 8;
        foreach ($values as $token) {
            if ($token == 'X') {
                $token = 10;
            }
            $check += ($token * $multi);
             -- $multi;
        }
        $check %= 11;
        $check = 11 - $check;
        if ($check == $checksum) {
            return true;
        } else 
            if (($check == 10) && ($checksum == 'X')) {
                return true;
            }
        return false;
    }

}
